This application claims the benefit of Korean Application No. 2000-57690, filed Sep. 30, 2000, in the Korean Patent Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to an ink jet printer head, and more particularly, to an ink jet printer head capable of increasing printing efficiency and quality by improving a structure of an ink passage, to decreas ink back flow backflow and improve an ink droplet shape.
2. Description of the Related Art
Generally, an ink jet printer head uses a thermal driving method or a piezoelectric driving method to discharge ink. According to the thermal driving method, ink is instantly heated by a heat resisting body, generating a bubble. As the bubble is inflated, ink is discharged to a nozzle hole by the pressure of the bubble. According to the piezoelectric driving method, ink is discharged to a nozzle hole by the force applied from the displacement of a piezoelectric body.
Conventional thermal driving ink jet printer heads are grouped into two types based upon a discharge direction with respect to a substrate and a nozzle plate: (1) a side shooting type (as shown in FIG. 1A) and (2) an upper surface shooting type (as shown in FIG. 1B).
According to the side shooting type ink jet printer head 10 of FIG. 1A, a nozzle hole 16 is formed at one side end portion of an ink channel 13, which is formed between a substrate 11 and a nozzle plate 12. A bubble 2 is generated from ink 1 of the ink channel 13, which is instantly heated by a thin film heat resisting body 14. Due to the growing pressure exerted by the bubble 2, the ink 1 is discharged from the nozzle hole 16 to the outside.
The upper surface shooting type ink jet printer head 20 of FIG. 1B comprises an ink chamber barrier 23, which is formed on a substrate 11 (not shown) on which a thin film radiating resistance body (not shown) is disposed to form an ink chamber 24 communicating with an ink channel 22, and a nozzle plate 25, which is formed on the ink chamber barrier 23 and has a nozzle hole 26 communicating with the ink chamber 24.
According to the ink jet printer head 20, the ink (not shown) of the ink chamber 24 is instantly heated by heating a thin film heat resisting body (not shown). A bubble (not shown) is generated from the heated ink and expands, creating pressure against an interior of the ink chamber 24, and discharging the ink to the outside through the nozzle hole 26.
However, in the conventional ink jet printer heads 10 and 20, an ink backflow phenomenon occurs due to an inflating pressure of the bubble 2, in which the ink 1 reverses into the ink channels 13 and 22. The ink backflow accompanies a cross-talk in the printing operation, and deteriorates the printing quality.
Furthermore, in the conventional ink jet printer heads 10 and 20, a tail is generated in a discharging ink drop when the bubble 2 decreases in size. The ink drop tail is extended by the surface tension and the viscosity of the ink 1. The ink drop tail generates several fragments, and accordingly decreases the resolution and print quality.
In order to overcome the above-mentioned problems, in the conventional side shooting type ink jet printer head 10, the length of the ink channel 13 is increased to restrain the generation of the backflow and the ink drop tail. However, such a structure increases the size of the ink jet printer head and decreases the ink discharging efficiency.
In the upper surface shooting type ink jet printer head 20, a neck is formed by machining step portions 23a and 23b in the ink channel 22 of the ink chamber barrier 23, formed on substrate 21, to restrain the backflow of the ink. However, such a structure requires a complex manufacturing process. Also, because the height of the ink channel 22 formed between the ink chamber 24 and the nozzle plate 25 remains constant, printer efficiency is restricted.
Accordingly, it is an object of the present invention to solve the above-mentioned problems of the conventional printer heads. It is another object of the present invention to provide an ink jet printer head with increased printing efficiency and printing quality.
It is a further object of the present invention to provide an ink jet printer head with an improved ink passage, reduced backflow, and improved [the shape of the] ink droplet shape.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and, in part, will be obvious from the description, or may be learned by practice of the invention.
The foregoing objects of the present invention are achieved by providing an ink jet printer head including a substrate having a heat resisting body, an ink chamber barrier installed on the substrate to form a side wall of an ink chamber filled with ink introduced through an ink channel, and a nozzle plate having a nozzle hole formed to communicate with the ink chamber and installed on the ink chamber barrier. An ink separating wall protrudes from the periphery of the nozzle hole towards the substrate so as to be located on the ink channel to interrupt the flow of the ink provided in the nozzle plate.